diff --git a/toonz/sources/common/tgeometry/tgeometry.cpp b/toonz/sources/common/tgeometry/tgeometry.cpp
index cbd9367..4fa6543 100644
--- a/toonz/sources/common/tgeometry/tgeometry.cpp
+++ b/toonz/sources/common/tgeometry/tgeometry.cpp
@@ -368,8 +368,6 @@ TAffine4 TAffine4::rotationZ(double angle) {
 
 //==================================================================================================
 
-const TAngleRangeSet::Type TAngleRangeSet::Iterator::m_blank = TAngleRangeSet::Type();
-
 
 int TAngleRangeSet::find(Type a) const {
   assert(!m_angles.empty());
diff --git a/toonz/sources/include/tgeometry.h b/toonz/sources/include/tgeometry.h
index 6faae14..58afecf 100644
--- a/toonz/sources/include/tgeometry.h
+++ b/toonz/sources/include/tgeometry.h
@@ -1341,6 +1341,7 @@ public:
   typedef TAngleI Type;
   typedef std::vector<Type> List;
 
+  static const Type min = Type();
   static const Type max = Type() - Type(1);
   static const Type half = ((Type() - Type(1)) >> 1) + Type(1);
 
@@ -1365,7 +1366,6 @@ public:
     List::const_iterator m_end;
     List::const_iterator m_current;
     bool m_lapped;
-    static const Type m_blank;
 
   public:
     inline Iterator(): m_flip(), m_lapped(true)
@@ -1408,10 +1408,10 @@ public:
     inline Iterator& set(const TAngleRangeSet &ranges, bool flip = false, bool reverse = false)
       { return set(ranges.angles(), ranges.isFlipped() != flip, reverse); }
 
-    inline const Type& a0() const
-      { return valid() ? *(m_current == m_begin ? m_prebegin : m_current - 1) : m_blank; }
-    inline const Type& a1() const
-      { return valid() ? *m_current : m_blank; }
+    inline const Type a0() const
+      { return valid() ? *(m_current == m_begin ? m_prebegin : m_current - 1) : Type(); }
+    inline const Type a1() const
+      { return valid() ? *m_current : Type(); }
     inline double d0() const
       { return toDouble(a0()); }
     inline double d1() const
diff --git a/toonz/sources/tnztools/assistants/assistantellipse.cpp b/toonz/sources/tnztools/assistants/assistantellipse.cpp
index 9a2c5c0..236c6a7 100644
--- a/toonz/sources/tnztools/assistants/assistantellipse.cpp
+++ b/toonz/sources/tnztools/assistants/assistantellipse.cpp
@@ -16,7 +16,7 @@
 //    TAssistantEllipse implementation
 //*****************************************************************************************
 
-class DVAPI TAssistantEllipse final : public TAssistant {
+class TAssistantEllipse final : public TAssistant {
   Q_DECLARE_TR_FUNCTIONS(TAssistantEllipse)
 public:
   const TStringId m_idRestricktA;
diff --git a/toonz/sources/tnztools/assistants/assistantline.cpp b/toonz/sources/tnztools/assistants/assistantline.cpp
index ff2a9b4..a306f7b 100644
--- a/toonz/sources/tnztools/assistants/assistantline.cpp
+++ b/toonz/sources/tnztools/assistants/assistantline.cpp
@@ -13,7 +13,7 @@
 //    TAssistantLine implementation
 //*****************************************************************************************
 
-class DVAPI TAssistantLine final : public TAssistant {
+class TAssistantLine final : public TAssistant {
   Q_DECLARE_TR_FUNCTIONS(TAssistantVanishingPoint)
 public:
   const TStringId m_idRestricktA;
diff --git a/toonz/sources/tnztools/assistants/assistantvanishingpoint.cpp b/toonz/sources/tnztools/assistants/assistantvanishingpoint.cpp
index 94867e0..b660e60 100644
--- a/toonz/sources/tnztools/assistants/assistantvanishingpoint.cpp
+++ b/toonz/sources/tnztools/assistants/assistantvanishingpoint.cpp
@@ -12,7 +12,7 @@
 //    TAssistantVanishingPoint implementation
 //*****************************************************************************************
 
-class DVAPI TAssistantVanishingPoint final : public TAssistant {
+class TAssistantVanishingPoint final : public TAssistant {
   Q_DECLARE_TR_FUNCTIONS(TAssistantVanishingPoint)
 public:
   const TStringId m_idPassThrough;